Browsing: knives

Lone Wolf, Diablo double and more…

Here are brief looks at knives that have crossed my desk and caught my attention. Kershaw Knives R.A.M. Model 1919 is designed by the father and son knife making team of Grant and Gavin Hawk. It has a 3 1/8 inch Sandvik 12C26 stainless steel blade, a handle made out of 6061-T6 black anodized aluminum and a textured black G-10 overlay, it’s a dandy folder. If that’s all there was to the R.A.M it would be well worth its price of $99.99.

However the R.A.M. is a pseudo assisted opening folder. What I mean by this is not an assisted opener. What the R.A.M. has is something like a pump that locks the blade opened (and closed). And with the flipper you just give it a slight push and the blade swings open. It actually feels like it’s assisted but it’s not. It’s the pressure of the pump that feels like it’s assisted. But it’s not. It’s the pressure of the pump that feels like it’s assisting the blade open. There are three tine thumb studs on both sides of the blade, but I found them all pretty much useless. I preferred the flipper for opening this knife.

I’ve always been a fan of the Paul knife, designed by Paul W. Poehlmann. However I always thought they were a bit too small to my liking. They are, without a doubt true gentleman’s knives. I like the patented Paul Axial locking device on the Paul knives, it always struck me as brutally strong.

Lone Wolf has introduced a larger sized Paul knife with a 3 ½ inch blade made out of 154 CM high carbon stainless steel. The carbon fiber handle scales and the size of the knife makes it fall into the tactical folder category, although the sleek lines of the Paul Knife could make it fall into the gent’s knife category. This is the first Paul knife with pocket clip, adding to utility of the folder. At $189.99 it’s not cheap but then again, quality never comes cheap, and it is made in the USA.

A new version of Lone Wolf’s popular Diablo Double Action (DA) retains the folder that can be opened two ways: either using the thumb stud or the automatic method a switchblade if you live in a state that allows automatic knives. This new Diablo DA has 1 3/3 inch CPM-S30V Ti-Ni black coated blade. The handle scaler are dark green and black micarta. One thing you will notice with any of the Lone Wolf automatic folders is that the blades really pop out when activated. You have to hold onto these hummers or they’ll fly out of your hand as the blade flings open.

Something I really like about the Diablo DA line of automatic folders is the fact that the opening method is hidden. There isn’t any button to push. Instead the blade is opened by sliding the left side handle scale a fraction of an inch to one side, and the blade pops open. It’s like magic. I’ve won more than a couple bucks from folks who thought they could figure out how to open. Retail price on the Diablo DA with the green and black micarta-handle scales is $289.99

SOG knives visionary I and the Visionary II are a combination from two other knives in the SOG lineup. Both VG-10 stainless steel blades that are black powder coated. The visionary I has a 3 inch blade while the visionary II has a 3 ¾ inch blade. Both knives have Zytel handles with stainless steel liners, and have reversible pocket clips for right or left hand carry. Both models also have the Arc Lock ad they have been tested to withstand more than 1.000 pounds of pressure while still holding the table open.

The visionary I retails for $140 and Visionary II retails for $160. If I spread dozens of knives out on a table and picked the ones that had the most appeal, these would be the knives. Check them out at your local knife show or retailer and see if you agree.

Testing for Sharpness

First, I checked for sharpness. It is commonly known that some ultra-0smooth edges will slice through non-fibrous materials better than fibrous ones. But if you think about it, even a piece of meat has fibrous tendons in it. Many vegetables can also be quite fibrous. I needed to find a test material that would be fibrous in nature but still require an extremely sharp edge to cut cleanly. There are many different ideas on the best was to check for sharpness. Some are better than others. At the fore font of sharpness checking demonstrate the sharpness of edges. The main problem is determining and quantifying how easily the edge shaves. Also you end up using more of a shearing cut than a slicing one. Remember, all the edges in the photos will shave hair easily. Slicing paper is also used as a test of sharpness. Most papers are very easy to slice smoothly, but a few delicate papers such as cigarette and onionskin papers are much more difficult.

Several of these papers also seem to be directional in the orientation of the fibers, making them easier to cut in one direction than the other. I tried several brands of paper and found that Zig Zag seemed to be the most consistent and the most difficult to cut across the short dimension.
As I started slicing paper, my misconceptions started surfacing. I had always thought that the smoother that edge was, the better it would cut- period. At a hardness of 58.5 HRC all the edges except D and F would slice the cigarette paper across the short dimension. Just as I had expected, it was most difficult with A, easier with B, easier yet with C and E, but been impossible to verify that all the teeth had been polished off without a microscope. The few teeth left on the edge would allow the blade to start the cut in the paper. That in turn, would mislead me into thinking that the stopped edges both sheared a sliced better than those having a tooth. The real problem with my theories started to come out when I started to look at how the edges wore. Here things can get very complicated.

Testing for Edge Wear

I sliced through corrugated cardboard for my wear tests. I used it because it was cheap, consistent, and available and dulls edges fairly quickly. I used a slicing type action to get through the cardboard instead of shearing it. Slicing is how most knives are used in the real world and dulls a knife faster than shearing. I sliced up 1x 2 squares with each edge finish and then examined them under the microscope. As I expected, edge A cut with the most difficulty while wearing to a larger sharply-toothed edge. It would still shave with difficulty but not cut the paper. B wore to something resembling A, after the same amount of cutting. The larger teeth had sharp edges and were not rounded off. Shaving was quite easy and it would still barely cut the paper. Then it happened. Edge C wore to something resembling edge D and would barely shave at all. Trying to cut the paper was like a bad joke. Remember, this was all done with the same blade.

Then, edge D wore to an edge that still looked like D but with a slightly rounded edge and no shaving at all. Something had happened between edges B and C. So now I had a problem. I thought the problem might be hardness, so I re hardened the blade and left it at 60.0 HRC. Then, the edges performed more like I would have expected. All the edges wore to a coarser tooth, except for D, which still rounded off. Edge C cut so well that I had slice up two additional pieces of cardboard before I started to notice any significant wear. When it did wear this time, it went to a coarser tooth with sharp edges. I was surprised that a hardness difference of only 1.5 HRC would make such a change.

I also did a little testing with a factory stainless. The tests were performed quickly as I was running out of time and only wanted to get a general idea of what was happening. The most important result was that all the edge finishes seemed to wear to a round smooth edge instead of a sharp, larger tooth. Another variable not even considered here is the actual angle at the edge. I am sure that varying the angle will affect the changeover point between the edges that wears to one having sharp teeth or one that becomes smooth. As you can well guess, my lecture at the seminar was a little fragmented and without a great deal of detail. The good part was that I learned a lot and have a completely new direction to explore.

Current Practice

Currently I am sharpening all of my blades to the finest tooth edge I can get that will not wear smooth. If the edge is continually wearing to a coarser tooth having sharp edges, the effective useful life of the edge is increased. If the edge is just rounding off, the useful life will be very short. For most of my steels and Damascus I am finishing with an Ultra Fine grit Spyderco stone. The blade hardness is usually about 60.0 HRC. You might think that 60.0 HRC is too hard and brittle for a blade. I salt bath mar temper and freeze my blades in liquid nitrogen, thus reducing the brittleness problem greatly but, that is the subject for another article. I have eliminated all leather stropping with compound.

A light strop on denim is used to clean the junk out of the teeth formed by the stones, but I want to leave the micro teeth in place. If I have the opportunity to make a knife that will only cut fleshy materials and never anything fibrous, I will consider stropping and polishing the edge. Please remember that these results are only preliminary. Different knives on a different day might show entirely different results. I have a great number of samples to make and tests to run now. This winter I will be running tests to try and figure out exactly what is going on. I will be including samples to investigate how steel choice, heat, treating, edge geometry and surface finish all affect sharpness and edge holding. If you have any comments or suggestions I would be glad to hear them. I am in many ways learning to sharpen all over again.